Performance issue in CDHDR & CDPOS

I'm having the below QUERY on CDHDR which take a <bowdlerized> lot of time:

SELECT OBJECTCLAS

OBJECTID

CHANGENR

TCODE

UDATE

UTIME

INTO TABLE IT_CDHDR2

FROM CDHDR

WHERE OBJECTCLAS = C_OBJECT

AND OBJECTID = C_OBJECT

AND ( TCODE = C_TCODE1 OR

TCODE = C_TCODE2 ).

Then I've the other select query on CDPOS using for all entries on IT_CDHDR2. Both the queries are taking a lot of time.in the CDPOS select query I'm passing all the keys in order while I couldn't do that for CDHDR. Kindly advise if anyone has worked on the performance issues with CDHDR/CDPOS. What are all the possible ways of improving the performance of CDHDR / CDPOS.